Harbeth is a good match with PASS, but it will be a bit "laid-back", not in a bad way, it will work very well with acoustic, vocal, jazz, classical, however if you're into AC/DC or Metal music types, it will not be a good match. My opinion as I own the Harbeth 30.2s and almost went with a PASS with them.
@mr_m - but then you'd really need four 901's, one in each corner and then play Dark Side of the Moon at full volume with a 200 watt 4-channel Pioneer receiver from 1982....not that I ever did that of course.....